When taking a picture, it is necessary to know not only in what direction to aim the camera but also how much of the subject will be included in the picture. For this reason practically every camera has a viewfinder of some kind for framing the subject.
There are known cameras that are intended to take pictures having various formats. For example, the pictures may be interspersed full-size exposures about 36.6 mm.times.24.4 mm (length.times.height) and reduced-height panoramic exposures about 36.6 mm.times.13.3 mm. The viewfinder for these cameras has a masking device for changing the format of the view through the viewfinder in accordance with the format of the exposure to be made.
Other cameras are intended to make exposures having the same format. However, the viewfinder for these cameras has a masking device for changing the format of the view through the viewfinder in accordance with the format desired for a print to be made from the exposure. In this instance, the exposure is provided with an encodement that indicates the format desired for the print.
Conversely, prior art U.S. Pat. No. 4,283,860, issued Aug. 18, 1981, discloses a folding variable format viewfinder comprising a fixed first-format viewing aperture and movable second-format, third-format, fourth-format, and fifth-format viewing apertures pivotally connected to respective sides of the first-format viewing aperture for manual folding successively over the first-format viewing aperture. The first-format viewing aperture approximates the field of view of a 28 mm taking lens. The second-format viewing aperture approximates the field of view of a 35 mm taking lens. The third-format viewing aperture approximates the field of view of a 55 mm taking lens. The fourth-format viewing aperture approximates the field of view of a 135 mm taking lens. The fifth-format viewing aperture approximates the field of view of a 200 mm taking lens.